The broad, long-term objective is to complete the analysis of a large body of data already collected for a total, unselected population of young people with mental retardation (MR), who span the entire range of MR, born in Aberdeen, Scotland during a 5-year period and studied prospectively from birth to age 22. A non-retarded comparison population is also included in the study. Data have been collapsed into summary variables, and these will be used in complex multivariate statistical procedures to maximum use of this unique data set. First, cluster analysis will be used to develop a typology of the young adults, using variables that rate their abilities, disabilities, and functioning. A family typology will also be developed using cluster analytic procedures and will include the families of the nonretarded comparison subjects. The typologies will provide, for the first time, comprehensive descriptions of a total MR population and their families. Further, the typologies will be used to examine whether particular types of R children come from particular types of families; the similarities and differences in the subtypes of families found in the MR population and in the families of nonretarded comparison subjects; and the variability that occurs in the various adult roles and functioning of the R young adults who disappear from MR services after leaving school. In addition, a set of multivariate procedures will be used to determined the relative contribution of characteristics of the individual and the environmental in childhood to young adult adjustment.